Rice Quarterly: Spotlight on Rice Research

August 01, 2004
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by Emily Buckley

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Advances in research, from preharvest to processing and storage, were highlighted at this year’s University of Arkansas Rice Processing Program meeting

More than 70 industry and academic supporters of the University of Arkansas Rice Processing Program (UARPP) came from around the world to Fayetteville, Arkansas, U.S. in May, to discuss recent advances in rice processing research.

The meeting opened with current projects in pre-harvest property characterization of rice.

Recent investigations of the distributions of kernel-to-kernel breaking force — a measure of the rice kernel’s physical strength — have revealed that milling quality, as measured by head rice yield, or the amount of kernels that remain three-quarters of a kernel or more in length after milling, is proportional to the amount of strong kernels in a rice bulk.

The proportion of weak and strong kernels in a rice bulk can vary from one variety to another, but data presented showed that kernel-to-kernel breaking force distributions were similar across varieties at any given location in the U.S. Mid-South and varied from one location to another.

This has led UARPP researchers to look more closely at how location environment and soil type affect the variability of rice properties. A collaborative project between the University of Arkansas, RiceTec, Inc, producer of hybrid seed, and the Rice Research and Extension Center in Stuttgart, Arkansas, is quantifying the effects of nighttime temperature on rice quality variability and should provide a clearer understanding of the cause of processing quality variability incurred during production and possibly provide a means of improving rice varieties.

Another presentation described how thickness distributions of a rice bulk could be used to predict the physicochemical properties of rice. Studies on thin, medium and thick rice fractions showed that as the amount of thick kernels increases, so do the amylose content and the peak viscosity, while amylase and protein content decreases. Harvest moisture content and location affected the kernel thickness distributions, green kernel content, fissured kernel content and head rice yield of the tested rice bulks.

A presentation on the effects of soaking/rewetting of rice at various moisture contents revealed that the lower the initial moisture content of the rice before rewetting, the greater the reduction in head rice yield. Processors can use this information to make recommendations to producers on harvesting practices that would improve rice quality.

RICE DRYING AND STORAGE

University of Arkansas researcher, Canchun Jia, demonstrated a recently developed computer program, the BinDryer. This user-friendly software simulates the grain and air conditions in farm bins, allowing the user to calculate the optimum drying conditions and drying time for a rice bulk. The program will also work with other grains such as wheat, barley and sorghum.

Kansas State University-affiliated USDA entomologists Dr. Frank Arthur and Dr. Micheal Toews presented research pertaining to insect management using aeration and to the detection of internal insects in rice using digital X-rays and CAT scans. Texas A&M-affiliated USDA entomologist Dr. Ted Wilson spoke about a recently developed insect computer prediction model. UA researchers presented projects using infrared rays to destroy rice weevils and to accelerate the aging of rice.

RICE MILLING

A popular topic was the assessment of degree of milling (DOM), or the amount of bran removed during milling of rice. As there is currently no clear standard for measuring DOM, UA researchers have developed a reference method using the amount of lipids present on the outer surface of the milled rice kernel as a quantifier of DOM. It was shown that DOM can vary with variety, storage duration, milling duration and location where the rice was grown.

The meeting closed with presentations on sensory analysis and end use processing of rice with an emphasis on the evaluation and prediction of cooked rice texture. Also, preliminary results from a project concerning the effect of rice constituents in determining rice functionality and aging could help in understanding changes that occur during storage and the subsequent effect on cooked rice texture.

To emphasize the rice quality needs of brewers, Dr. Gary Hanning of Anheuser Busch described what his company looks for in "great brewing rice;" it should be high in amylose, low in protein, and low in lipids, he said.

Don McCaskill presented an overview of Riceland Foods’ new rice variety screening program, which is designed to address the needs of rice growers, millers, processors and consumers

by evaluating the quality characteristics of current and future rice varieties that will lead to the development of superior varieties of rice.

This year’s keynote speaker, Dr. Melissa Fitzgerald, described the role of the new Grain Quality and Micronutrient Center, of which she has recently been appointed director, at the International Rice Research Institute (IRRI) in the Philippines.

Construction of the new Grain Quality and Micronutrient Center began in May. The Center’s mandate is to identify high quality breeding lines through early screening for quality characteristics such as protein, lipid and amylose content, chalkiness, head rice yield, cooking characteristics, amylopectin fine structure, etc. Of particular interest in the Asian market, where most of the population’s caloric intake comes from rice, is the level of rice micronutrients, such as magnesium and potassium. The Center will screen for and explore optimization of micronutrient levels in potential rice varieties.

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Ground-breaking rice breeders win World Food Prize

Two rice researchers were honored in March as the winners of the 2004 World Food Prize. The scientists were lauded for their "breakthrough scientific achievements, which have significantly increased food security for millions of people from Asia to Africa."

Professor Yuan Longping of China, Director-General of the China National Hybrid Rice Research and Development Center in Changsha, Hunan, China was selected for his breakthrough achievement in the early 1970s in developing the genetic tools that have led to the world’s first successful and widely grown hybrid rice varieties, with yields 20% above conventional varieties. His achievements dramatically increased rice yields and grain output in China, providing food for an additional 60 million people each year. His approach is now being adapted to many other countries in Asia and worldwide.

Dr. Monty Jones of Sierra Leone, was selected for developing in the 1990s the "New Rice for Africa," uniquely adapted to the growing conditions of West Africa, by successfully crossing Asian and African strains to produce drought and pest resistant, high yielding new rice varieties. His accomplishment is producing enhanced harvests for thousands of poor farmers.

Dr. Jones is Executive Secretary, Forum for Agricultural Research in Africa (FARA), in Accra, Ghana and a former senior rice breeder at the West Africa Rice Development Center (WARDA).

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The UARPP

The University of Arkansas Rice Processing Program (UARPP) encompasses research relating to the preharvest property characterization, drying, storage, milling and end-use processing of rice. An outreach function provides research results to the industry, and an educational component prepares undergraduate and graduate students for careers in the industry.

The next UARPP Industry Alliance Meeting will be May 25 – 26, 2005.

To learn more about the research projects featured during this meeting or about becoming a sponsor of the University of Arkansas Rice Processing Program, please contact Dr. Terry Siebenmorgen, tsiebenm@uark.edu, or Dr. Jean-François Meullenet, jfmeull@uark.edu.